scholarly journals Constraints for Cataclysmic Binary Evolution as Derived from Space Distributions

1984 ◽  
Vol 80 ◽  
pp. 363-385
Author(s):  
H. W. Duerbeck
Keyword(s):  
Stellar Populations ◽  
Recurrence Time ◽  
Type I ◽  
Symbiotic Stars ◽  
Late Type ◽  
Dwarf Novae ◽  
Space Density ◽  
Long Period ◽  
Mira Variables ◽  
Cataclysmic Binaries

AbstractSpace densities and galactic z-distributions of novae, recurrent novae, dwarf novae and symbiotic stars are newly determined and discussed in the context of earlier determinations. The data are then compared with the distributions of single and binary stars of possibly related types (late type giants, Mira variables, Algol systems, W UMa systems).Novae and dwarf novae have similar distributions, those of fairly young stellar populations. The observed space density of potential novae (novalike objects) indicates that the mean recurrence time of novae might be as small as a few hundred years, which leads, with given nova shell masses and mass transfer rates in the minimum stage, to a secular decrease of the masses of the components undergoing nova outbursts.Recurrent novae and symbiotic stars have distributions of older stellar populations, similar to those of late type giants and Mira variables.On the basis of galactic distribution, novae and dwarf novae are closely related and may be final stages of W UMa systems, as well as progenitors of supernovae of type I. A small fraction of W UMa systems seems to belong to an older population. If evolutionary transitions between these types of stars can be substantiated, the presence of a minority of novae and dwarf novae in globular clusters and of supernovae I in elliptical galaxies can be explained.Due to the lack of sufficiently well determined space distributions of Algol binaries, the suggestion that long-period Algol systems might be the progenitors of cataclysmic binaries can as yet neither be substantiated nor refuted. A very high space density of long-period Algol systems in the solar neighbourhood is derived. The observed space density of cataclysmic binaries could be explained by the transformation of a small percentage of the long-period Algol systems by common envelope evolution.

scholarly journals The OH Circumstellar Maser in Late-Type Stars

1980 ◽  
Vol 87 ◽  
pp. 549-550 ◽  
Author(s):  
Nguyen-Q-Rieu ◽  
V. Bujarrabal ◽  
J. Guibert ◽  
A. Omont
Keyword(s):  
Colour Index ◽  
Type I ◽  
The Sun ◽  
Type Ii ◽  
Late Type ◽  
Dust Shell ◽  
Ir Sources ◽  
Mira Variables

A recent investigation based upon the OH luminosity distribution (Nguyen-Q-Rieu et al. 1979) has shown that Type I OH sources associated with Mira variables (OH Miras) are weak OH sources and are therefore only detected within ∼1 kpc from the Sun. Type II OH-Miras, which are more intense and rarer than Type I OH-Miras, are probably more distant objects. The group of unidentified Type II OH-IR sources probably consists of Type II OH-Miras of high OH luminosity. The IR colour index, which is usually higher for Type II sources, suggests that they have a colder and denser dust shell.

scholarly journals Cataclysmic Binaries: Optical and Geometrical Thickness of Disks and the Visibility of the Primary Components

1992 ◽  
Vol 151 ◽  
pp. 83-90
Author(s):  
Józef. I. Smak
Keyword(s):  
Accretion Disks ◽  
White Dwarf ◽  
Vertical Direction ◽  
Central Star ◽  
List Type ◽  
Type Number ◽  
Dwarf Novae ◽  
Long Period ◽  
Cataclysmic Binaries ◽  
Inner Parts

Accretion disks in cataclysmic binaries are optically thick (in the vertical direction), except for the case of inner parts of cool disks in dwarf novae at quiescence, which are optically thin. In long period Algols disks are cool and optically thick; their atmospheres can be quite extensive.Except for inclinations close to i = 0°, disks obscure either one or both hemispheres of the central star, the obscuration being either partial or total. In particular: (a)In stationary accretion cataclysmic binaries (old novae and nova-like systems), at inclinations close to 90° the white dwarf is fully obscured; at i < 85° only its top hemisphere becomes visible.(b)In dwarf novae at quiescence, at inclinations close to 90°, the obscuration of the white dwarf is either complete (for disk radii Rd ≥ 4 × 1010 cm), or limited to its equatorial parts (for Rd ≤ 2 × 1010 cm); at i ≈ 85 – 88° the top hemisphere becomes fully visible, while the bottom hemisphere is fully obscured; at i < 85°, due to the low optical thickness of the inner disk, parts of the bottom hemisphere near the equator also become visible.(c)In long period Algols the situations is similar as under (a); in addition, depending on inclination, part of the obscuration can be due to the atmosphere of the disk.

scholarly journals Infrared studies of symbiotic stars

1982 ◽  
Vol 70 ◽  
pp. 27-42 ◽  
Author(s):  
David A. Allen
Keyword(s):  
Spectral Type ◽  
Dust Emission ◽  
Circumstellar Dust ◽  
Symbiotic Stars ◽  
Infrared Photometry ◽  
Late Type ◽  
Cool Component ◽  
Mira Variables ◽  
Infrared Studies

AbstractInfrared photometry and spectroscopy of symbiotic stars is reviewed. It is shown that at wavelengths beyond lym these systems are generally dominated by the cool star’s photosphere and, indeed, are indistinguishable from ordinary late-type giants. About 25% of symbiotic stars exhibit additional emission due to circumstellar dust. Most of the dusty systems probably involve Mira variables, the dust forming in the atmospheres of the Miras. In a few cases the dust is much cooler and the cool component hotter; the dust must then form in distant gas shielded from the hot component, perhaps by an acccretion disk.Spectroscopy at 2μm can be used to spectral type the cool components, even in the presence of some dust emission. Distances may thereby be estimated, though with some uncertainty.Spectroscopy at longer wavelengths reveals information about the dust itself. In most cases this dust appears to include silicate grains, which form in the oxygen-rich envelope of an M star. In the case of HD 330036, however, different emission features are found which suggest a carbon-rich environment.

scholarly journals IRAS Observations of Symbiotic Stars

1989 ◽  
Vol 106 ◽  
pp. 391-400 ◽  
Author(s):  
M. Parthasarathy ◽  
H.C. Bhatt
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Planetary Nebulae ◽  
Evolutionary Stage ◽  
Symbiotic Stars ◽  
Late Type ◽  
Mira Variables ◽  
Show Evidence ◽  
The Masses

AbstractOf the 129 symbiotic stars in Allen's (1984) catalogue, 42 were found to be IRAS sources. Of these 42 IRAS sources, 22 are D-type (symbiotic Miras), 5 are D'-type (yellow symbiotics) and 15 are S-type. The separation of S, D and D’ types into three distinct groups is clearer in the log[fλ(25μm)/fλ(12μm)] versus (H-K) diagram. The IRAS fluxes of S-type symbiotics are consistent with that observed from normal M giants. This result suggests that mass-loss rate from most of the S-type symbiotics is similar to that from normal M giants. The IRAS data of D-type symbiotics shows evidence for the presence of dust envelopes. The masses of the dust envelopes (10-6 to 10-7 Mo) around Miras in D-type symbiotics are similar to that observed in field Mira variables. These results suggest that mass-loss rates in symbiotic Miras are similar to those from field Mira variables and also that the mass loss from symbiotic Miras is pulsationally driven similar to that found in field Mira variables by Whitelock, Pottasch and Feast (1987). Analysis of IRAS data of yellow symbiotics Ml-2, AS201, Cnl-1, Wray 157. and HD149427 suggests that they are young planetary nebulae containing a binary nucleus. Ml-2, AS201 and Cnl-1 show evidence for the presence of evolved hot companions. The evolutionary stage of the late type (F-G) companions is not clear.

scholarly journals The Metallicity Distribution of Late Type Dwarfs

1998 ◽  
Vol 11 (1) ◽  
pp. 571-571
Author(s):  
M. Haywood ◽  
J. Palasi ◽  
A. Gómez ◽  
L. Meillon Dasgal
Keyword(s):  
Star Formation Rate ◽  
Formation Rate ◽  
Angular Separation ◽  
Stellar Populations ◽  
Late Type ◽  
Limited Sample ◽  
Hipparcos Catalogue ◽  
Galactic Stellar Populations ◽  
Metallicity Distribution ◽  
Hr Diagram

The Hipparcos catalogue provides an accurate and extensive sampling of the solar neighbourhood HR diagram. The morphology of this diagram depends on selection criteria of the catalogue such as the limiting magnitude, angular separation and on the characteristics of the stellar populations near the sun (space density, metallicity, star formation rate, etc). Since the Hipparcos data are so accurate, one needs to model precisely the different selection bias and, at the same time, parametrize models of the galactic stellar populations with sufficient flexibility that as much information as possible can be grasped from the catalogue. Comparisons between our model and the Hipparcos catalogue will be presented elsewhere. Since the quantity of information contained in the Hipparcoscatalogue is so important, models ought to be complex, and external contraints, obtained prior to any general comparison with the model, are welcome. A major factor that influences the distribution of the stars in the HR diagram is the metallicity. For the late type stars, the metallicity distribution can be best studied by re-analysing a volume-limited sample of stars from the catalogue.

scholarly journals The Pulsation of M-type Miras: Multi-Epoch ISO-SWS Observations and Dynamical Models

2002 ◽  
Vol 185 ◽  
pp. 538-541 ◽  
Author(s):  
B. Aringer ◽  
U.G. Jørgensen ◽  
F. Kerschbaum ◽  
J. Hron ◽  
S. Höfner
Keyword(s):  
Time Series ◽  
Radiative Transfer ◽  
Wavelength Range ◽  
Infrared Range ◽  
Dynamical Models ◽  
Long Period ◽  
Mira Variables ◽  
Long Period Variables ◽  
Hydrostatic Model ◽  
Additional Assumptions

AbstractWe present time series of observed and synthetic ISO-SWS spectra of oxygen-rich Mira variables covering the wavelength range between 2.36 and 7.75 μm. The calculations are based on new dynamical models, which have been computed with a non-grey radiative transfer taking into account all relevant molecular opacities. It turns out that many features in the ISO spectra of cool long period variables which could not be reproduced within the framework of classical hydrostatic model atmospheres nor with grey dynamical calculations can now be understood without any additional assumptions. This is especially true for the water bands, which dominate the opacity in the infrared range of M-type Miras.

scholarly journals The evolutionary status of symbiotic stars

1982 ◽  
Vol 70 ◽  
pp. 275-282 ◽  
Author(s):  
Bronislaw Rudak
Keyword(s):  
Cataclysmic Variables ◽  
Evolutionary Status ◽  
Spherically Symmetric ◽  
Symbiotic Stars ◽  
Transfer Phase ◽  
Common Envelope ◽  
Long Period ◽  
Red Giant ◽  
Detached Binaries ◽  
Rapid Mass

AbstractThe evolutionary relations between symbiotic stars and cataclysmic variables are presented. The symbiotic stars are assumed to be long period detached binaries containing a carbon-oxygen degenerate primary and a red giant losing its mass through a spherically symmetric wind. Such systems can be obtained in Case C evolution, provided a common envelope during a rapid mass transfer phase was not formed. The same way recurrent novae containing a red giant as a secondary component may be produced. The factors influencing the differences between symbiotic stars and nova-type stars are discussed.

The nova type outburst of the symbiotic star AS 296

1990 ◽  
Vol 122 ◽  
pp. 440-441
Author(s):  
Ulisse Munari
Keyword(s):  
Orbital Period ◽  
Active Phase ◽  
Borderline Case ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Late Type ◽  
Type Giant ◽  
One Year

AbstractThe photometric and spectroscopic evolutions, displayed by AS 296 since the June 1988 outburst ([1]), are presented and discussed. The main features of the model outlined by [2], [3] and [4], are confirmed and further developped. An orbital period of about 3 years is inferred from Hα modulation (see [5]).The outburst originated from a TNR event in the accreted envelope of a WD. The IUE and optical spectroscopic evolution agrees with the expected scenario for degenerate conditions in the accreted material, while the high quiescence luminosity of the WD would indicate nondegenerate conditions.The late type giant passed unchanged the outburst. Also the region of Hα formation was not touched by the eruption.After one year the system has not yet reached the quiescence again. The photometric evolution displayed by AS 296 up to June 15, 1989 is presented in Fig.1.In Tab.1, the main features exhibited by symbiotic stars that have experienced a TNR event are summarized. The first 8 objects in the table are usually collectively called "symbiotic novae". They distinguish themselves for the very long outburst duration. At present, AS 296 appears to be a borderline case of such class, and a firm understanding needs to wait for the end of current active phase.

scholarly journals The Galactic Distribution of OH/IR Stars

1977 ◽  
Vol 42 ◽  
pp. 399-433
Author(s):  
H.J. Habing
Keyword(s):  
Present Status ◽  
Line Emission ◽  
Microwave Line ◽  
Late Type ◽  
Maser Emission ◽  
Long Period ◽  
Ir Stars ◽  
Long Period Variables ◽  
Recent Compilation ◽  
Galactic Distribution

In 1967 Wilson and Barrett (1968, 1970) discovered that some long period variables, very red and apparently very late type stars, emit OH microwave line emission that is especially strong in the 1612 MHz line at 18 cm. At present some 65 such OH-emitting stars have been identified - for a recent compilation see Bowers and Kerr (1977, M giants) and Baudry et al. (1977, M supergiants). Several stars show maser emission in H2O and SiO as well. At this colloquium Winnberg will review the present status of our knowledge of these stars.

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